Textile fibers and process for dyeing same



United States Patent Ofi ice 3,l73,?d7 Patented Mar. 16, 1965 3,173,747 TEXTILE FIBERS AND PRQCESS FOR DYEING SAME Beniamin De Laney Wyse, 53:, Camden, S.(Z., assignor to E. I. du Pont de Nemours and Company, Wilmington, Del., a corporation of Delaware No Drawing. Filed Sept. 22, 1961, Ser. No. 139,855 13 Claims. (Ci. S- -SS) This invention relates to acrylonitrile polymers which exhibit level dyeing characteristics when dyed with basic dyestufis. More particularly, this invention relates to a process for level dyeing single component and composite or mold-component fibers of acrylonitrile polymers which normally dye at unusually high rates due to the presence of anionic groups on the polymer chains.

It is known that in dyeing acrylonitrile polymer fibers basic dyestuifs can be used. The dyeings obtained are generally even in shading and have good fastness properties. Difficulty has been encountered, however, in obtaining good level dyeing in fibers prepared from aciylonitrile polymers having a large number of anionic groups, i.e., sulfate and sulfonate substituents, on the polymer chain. Non-unit rmities appear due to the rapid exhaustion of the dyestutf from the bath. Even more diiiiculties occur in the union dyeing of blends of fibers having low and high anionic group contents. A particularly difiicult problem has been encountered in the dyeing of composite fiber structures in which dissimilar polymeric compositions extend in side-by-side relationship along the length of the fiber.

Considerable eflort has been devoted to developing processes which permit the retention of anionic substituents on the polymer chain while at the same time reducing the dyeing rate of the fibers. Retention of the anionic groups is necessary in composite structures in which the groups are present in different amounts in the polymeric components in order to provide bulking and reversible crimpability.

It is, therefore, an object of this invention to provide a process for level dyeing with basic dyestuffs acrylonitrile polymer fibers having a high anionic group content. It is another object of this invention to provide a process for reducing the dyeing rate of acrylonitrile polymer fibers having a high anionic group content without removing the anionic groups. A further object of this invention is to provide multi-component and single component acrylontrile polymer fibers which dye uniformly. Other objects of this invention will appear hereinafter.

The objects of this invention are accomplished by chemically combining a small percentage of magnesium with an acrylonitrile polymer having a large number of anionic groups on the polymer chain before shaping the polymer into fiber form, extruding the polymer to form the fibers, and thereafter conducting the dyeing in a dye bath containing a. basic dyestutl.

In one embodiment for carrying out the process of this invention, a magnesium salt, such as magnesium bisulfite, in an amount from about 0.1% to about 6% is added to the polymerization vessel as the activator in a conventional redox initiated polymerization system. By controlling the amount of the magnesium bisulfite initiator within the aforementioned limits and utilizing from about 1% to about 10% of an ethylenically unsaturated sulfonic acid which is copolymerizable with acryloni-trile, from about 0.01% to about 0.3% of magnesium is chemi cally combined in the polymer formed. The polymers so formed, which contain from about 50 to about 600 milli equivalents per kilogram of polymer of anionic groups, i.e., sulfonate and sulfate groups, may be formed into fibers by conventional extrusion processes. After the fibers are formed, dyeing is carried out in a usual dye bath containing a basic or cationic dye-stuff. Surprisingly the fibers containing the'large number of anionic groups and the combined magnesium dye atan even rate to full shades of uniform coloration.

By the expression milliequivalents per kilogram of polymer of anionic groups it is meant the number of milliliters of 1 N alkali which would be required to neutralize the combined sulfonate and sulfate 'substituents in a kilogram of polymerif all such 'substituents were in the free acid form.

Preferred embodiments of the invention are illustrated in the following examples in which proportions are given in parts by weight unless otherwise specified.

EXAMPLE 1 Preparation 0 magnesium bisulfite Into 4500 parts of water at room temperature was passed a stream of sulfur dioxide gas until the pH of the water solution reached about 3.0. While thoroughly mix ing to insure suspension, 58.3 parts of magnesium by droxide was added in small increments while continuing the addition of suliur dioxide. During the addition of the magnesium hydroxide, the temperature was 'main tained below 30 C. by external cooling, and the pH maintained below 5.0 by balancing the rates of addition of the two reagents. Within a few minutes after addition of the last increment of magnesium hydroxide, a clear solution of the reagent was obtained, which by analysis was found to contain 3.94% magnesium bisulfite, calculated as Mg(HSO plus approximately 1% excess sulfur dioxide. This reagent was found to be stable so long as an excess of sulfur dioxide was maintained. It was used as a polymerization activator with no further treatment.

EXAMPLE II To an overflow-type, jacketed, Wei-agitated polymerization vessel partly filled with water acidified with sulfur dioxide to a pH of 3.0 and heated to 55 C., the following ingredients were fed in the relative proportions indicated. An amount of soluble iron salt necessary to provide about 0.2 part per million of iron based on the total reaction mixture was dissolved in the water. Rates of flow were adjusted so that the reacting volume wasted in eighty minutes minutcs'hold-up time). Parts given are by weight of active ingredients.

Parts Acrylonitrile 20.68

Methyl acryla-te 132 Potassium persulfate, K S O 8.3

(As a 4% aqueous solution) Magnesium bisulfite, Mg(HSQ 44 (As a 3.94% aqueous solution) Sulfur dioxide About 6 (To main pHat 30:02)

Sodium styrenesulfonate 6.2

(As a 1% aqueous solution) Separate water flow 375 7 An atmosphere of inertgas, mainly nitrogen andcarhon dioxide, was maintained in the polymerization vessel, and the temperature was held at 55 C. by refrigerated water circulated through the jacket. Polymerization was terminated in the reaction-mixture overflowing from the vessel by addition of an amount of the sodium salt of ethylene diamine tetra acetic acid necessary to complex the soluble iron catalyst. The-polymer was continuously filtered oil, washed free of residual catalystand activator, try-product salts, and unreacte'd monomers and then dried to below 1% moisture at a temperature of 108 C. At this time, conversion of monomers to polymer amounted to 73%, the terpolymcr had an intrinsic viscosity of 1.45,

of sodium styrenesulfonate of that example.

and it was found to contain 52 milliequivalents per kilo gram of s ulfonate and sulfate groups attached to the polymer chain. The polymer contained 0.18% magnesium which could not. be extracted by prolonged washing with warm water.

EXAMPLE III The polymerizing vessel used in Example II was filled to the /2 mark with demineralized water acidified by sulfur dioxide to a pH of 2.9. The vessel free space was then swept with an inert gas until the contained atmosphere analyzed less than 1% oxygen, while the water solution of sulfur dioxide was heated to approximately 55 C. by circulation of a heating medium in the jacket. The following materials were then added at such a rate, and in the proportions by weight (based on active ingredients) as given below, that the vessel overflowed in about 55 minutes. At this rate of addition, hold up time was 110 minutes. During the entire reaction the temperature was maintained at 55 C. plus or minus 2 C. by jacket refrigeration. The separate Water flow contained the small amount of soluble iron salt required to maintain 0.2 ppm. iron, based on total reactants, including water.

Parts by weight Acyrlonitrile 1925 Sodium styrenesulfonate 75 (As a 4% aqueous solution) Magnesium bisulfite, Mg(HSO 37 (As a 3.94% aqueous solution) Potassium persulfate, K S O 3.5

(As a 3.0% aqueous solution) Sulfur dioxide, S About 5 (To control pH at about 3.0)

.Demineralized water 5640 Within about six hours, substantial equilibrium was reached, and the overflowing polymer slurry was found to represent 79% conversion to polymer of the monomers fed. Termination of the polymerization and isolation of the polymer was accomplished as described in Example II. The intrinsic viscosity of the product was found to be 1.54. Analysis of this polymer revealed 260 milliequivalents per kilogram of sulfonate and sulfate groups attached to the polymer chain. Combined magnesium averaged 0.24% with a range of from 0.22% to 0.28%

EXAMPLE IV The procedure outlined in Example III was duplicated except that the sodium styrenesulfonate was reduced to 39 parts and the catalyst (K S O reduced to 2.8 parts. Of the monomers fed, 75% were reacted to yield a poly mer of 2.0 intrinsic viscosity which contained 148 milliequivalents per kilogram of sulfonate and sulfate groups attached to the polymer chain. Combined magnesium averaged 0.16% with a range in the analyses from 0.13% to 0.23%.

EXAMPLE V The procedure of Example III was followed, except that the sodium styrenesulfonate was reduced to 39 parts and the magnesium bisulfite activator solution was replaced by a 3.0% solution of sodium bisulfite (calculated as Na S O the same parts, active basis, being employed). The product was a copolymer of acrylonitrile and sodium styrenesulfonate of 2.0 intrinsic viscosity which contained, by analysis, 148 milliequivalents per kilogram of sulfonate and sulfate groups attached to the polymer chain. Approximately 77% of the monomers were converted to polymer.

EXAMPLE VI The procedure of Example II was followed, except that 19.9 parts of sodium allyl sulfonate replaced the 5.7 parts After six hours, 74% of the monomers fed were continuously converted to polymer of 1.35 intrinsic viscosity and 56.5

milliequivalents per kilogram of sulfonate and sulfate groups on the polymer chain. In this case, the sulfonate modifier did not completely polymerize. Combined magnesium found: 0.18%.

EXAMPLE VII Example II was repeated except that 4-4 parts of sodium bisulfite (calculated as Na S O a 20% solution in water being employed) replaced the magnesium bisulfite, and 15.5 parts of magnesium sulfate (calculated as the anhydrous salts) was added; The polymer after being thoroughly washed with warm water Was found to contain 0.18% of combined magnesium.

EXAMPLE VIII An acrylonitrile/ sodium styrenesulfonate copolymer was prepared according to the procedure described in Example III except that the magnesium bisulfite solution was replaced by a 20% solution of sodium bisulfite (calculated as Na S O the same parts being used), and approximately 4.0 parts of potassium persulfate was used. The product, representing a conversion of 79%, had an intrinsic viscosity of 1.50 and contained 260 milliequivalents per kilogram of sulfate and sulfonate groups on the polymer chain.

EXAMPLE ]X EXAMPLE X Following the general procedure of Example III, a homopolymer of acrylonitrile Was prepared by feeding the following ingredients at such a rate as to give a holdup time of 68 minutes to the vessel described in Example III.

Parts by weight Acrylonitrile 2200 Potassium persulfate (KzSgOg) (as a 4% aqueous solution) 2.0 Sodium bisuliite (Na S O (as a 20% aqueous solution) 22 Sulfur dioxide (to control pH at 3.1) About 4.2 Demineralized water 7,000

A conversion of monomer to polymer of approximately 68% Was realized. The product had an intrinsic viscosity of 2.00 and contained 27 millequivalents per kilogram of sulfonate and sulfate groups on the polymer chain. In this experiment, the sulfonate and sulfate groups were provided by the sodium bisulfite initiator.

EXAMPLE XI Dyeing of fibers-containing no combined magnesium A composite fiber was prepared by the process described in Example I of U.S. 2,988,420, employing the polymers of Examples VIII and V above. Neither of the polymers contained magnesium. In this experiment, 27% and 20% solutions, respectively, of the two polymers in dimethylformamide were simultaneously spun to provide approximately equal volurnes of the two solutions at each orifice of a spinneret. Thus, the copolymers of Examples VIII and X each represented approximately /2 of the filament cross section. Due to their eccentric relationship in the individual filaments and a differential in shrinkability between the two components, crimp developed spontaneously on boil-off of the finished product.

After extraction of residual solvent, drawing to four times their spun length, mechanically crimping for textile processability, cutting to 3% inch staple length and drying, the fiber was spunto/ 1 cotton count yarn, which wasthen knitted on a circular knitting machine to yield classic-type sweater bodies.

A dyebath was prepared as follows:

For each 100 parts of fabric to bedyed, 4,000 parts of an aqueous bath was prepared at room temperature to contain the following:

0.25 part Basic Blue dye, Cl. N0. 21 0.5 part glacial acetic acid 0.5 part of a leveling agent composedof a non-ionic condensation product of ethylene and propylene-oxides 10.0 parts of Glaubers salt (calculated as anhydrous 1.0 part of a retarder composed of a quaternary ammonium salt derived from naturally occurring fats The sweater bodies prepared according to this example were added to the bath which was then raised slowly to the boil, the rate of temperature increase being approximately 2 F. per minute. The bath was continuously boiled. for an additional one and one-half hours, cooled to approximately 120 1 and then removed. Thedyetl fabric. wasthen rinsed with warm water and examined; it had not dyed uniformly and presented a Streaky appearance. It was evident that a rapid. strike-on of the dye had not been leveled by the prolonger boiling.

EXAMPLE XII Dyeing of fibers containing magnesium.

The procedure. of the previous example, was followed except that polymer of Example III replaced the. polymer of Example VIII. In this case, the fabric dyed to about the sarne depth as in Example XI; however, it presented a uniformly dyed appearance, illustratingthat the retarding action of the combined magnesium cat-ionshad reduced the initial strikecn of the dye to an acceptable level.

EXAMPLT XIII 1.0% Basic Red dye, CI. No. 14

6.0% of a retarder composed of a quaternary ammonium salt derived from naturally occurring fats 10.0% Glaubers salt 0.5% of a non-ionic surfactant 0.5% glacial acetic acid 0.5% sodium acetate The dye, bath was brought to a boil and the staple pad added. The following tabulation shows the percent of bath exhaustion vs. time of dyeing at the boil for each of several dyeings:

Bath Exhaustion, percent Fiber of Example XII Fiber of Example XI 50 min This experiment shows that the rate of dyeing of the fiber containing the combined magnesium cation is substantially less than that of the fiber containing only the alkali cations. Complete exhaust of the bath within about 10 minutes is not amenable to control for uniformdyeing.

xhaustion within approximately one hour readily lends the dyeing process to controlling to provide uniform shades of the desired coloration.

EXAMPLE XIV Polymers of Examples Ii, VI, and VII, representing terpolymers containing combined magnesium, and the polymer of Example IX, a similar terpolyrner containing no magnesium, were individually spun from 28% solutions in dimethylformamide to form homo-fibers. Staple fiber pads were prepared by hand-carding fibers from each of the polymers. The pads were then dyed in a bath having the composition described in Example XI. The bath, in this experiment, was so large relative to the fiber to be dyed that the amount of dye taken up by the fiber made no significant change in the bath composition. The four staple fiber pads of this example were dyed simultaneously in the infinite dye bath for two hours at the boil. The results of several such dyeings showed the fibers prepared from polymers of Examples II, VI, and Vll to be essentially equivalent in dyeability with all pads being dyed uniformly and absorbing ap proximately 76% of the amount of dye absorbed by the fiber made from the polymer of Example IX which presented a streaked appearance.

EXAMPLE XV In a manner similar to that of Example XIV, a comparison was made of the dyeing rates of fibers produced from polymers of Example IV, containing magnesium, and Example V which contained no magnesium. Basic Violet. dye, CI. N0. 3, was substituted part for part for the dye of Example XIV. The fiber produced from polymer of Example IV dyed at a rate approximately onehalf as fast as the fiber prepared from the polymer of Example V.

As illustrated in the foregoing examples, by chemically combining magnesium with the high anionic content polymers before the formation of fibers, level dyeing is achieved. In preparing such polymers, the procedures described in US. 2,837,500 and 2,837,501 may be gen erally followed with the magnesium bisulfite being substituted for the sodium meta-bisulfite activator described in the patents. As illustrated in Example VII, the magnesium may also be introduced into the polymer by mixing a magnesium salt which is ionizable in the reaction mixture such as magnesium sulfate with the reactants during the polymerization.

As indicated in the aforementioned patents, the polymers will generally contain a major proportion of acrylonitrile, a small percentage of an ethylenically un saturated monomer which provides the anionic groups such as ethylenically unsaturated sulfonic acids and their water-soluble salts, and a minor proportion of a neutral ethylenically unsaturated monomer which is copolymerizable with acrylonitrile. In the initiator system the oxygen-yielding polymerization catalyst may be any of the typical catalysts such as those disclosed in U.S. 2,- 462,354.

In addition. to those acrylonitrile polymer compositions disclosed in the examples, fibers containing the requisite amount of magnesium may be prepared from a number of other copolymerizable monomers. Preferably the acrylonitrile component will comprise at least about of the polymers with a well-known copolymerizable ethylenically unsaturated monomer, such as one of those disclosed in US. 2,436,926, being present in an amount up to about 15% by weight of the polymers. The anionic groups will be provided by a copolymerizable ethylenical- 1y unsaturated sulfonic acid, e.g., styrene sulfonic acid, methallyl sulfonic acid, allyl sulfonic acid, ethylene sulfonic acid, or one of their water-soluble salts, in an amount from about 1% to about 10% by Weight of the polymer.

The process of the present invention has its greatest utility in dyeing composite fibers prepared from acrylonitrile polymers and copolymers having substantially different amounts of anionic groups on the respective polymer chains. Composite fibers prepared from such polymers and copolymers are disclosed in French Patent 1,205,162.. These fibers, which exhibit unique bulking properties due to the differential anionic group content, may be dyed to even colors by incorporating magnesium in the polymeric component containing the high number of anionic groups.

As many widely different embodiments of this invention may be made without departing from the spirit and scope thereof, it is to be understood that this invention is not to be limited to the specific embodiments thereof except as defined in the appended claims.

' I claim:

1. In a process for level dyeing with a basic dyestutf fibers of an acrylonitrile polymer having from about 50 to about 600 milliequivalents per kilogram of polymer of anionic groups attached to the polymer chain, the steps comprising chemically combining with said polymer before forming fibers therefrom from about 0.01% to about 0.3% by weight of magnesium, extruding said polymer to form said fibers, and thereafter conducting the dyeing of said fibers in a dye bath containing said basic dyestuff.

2. The process of claim 1 wherein said polymer is comprised of copolymerized monomeric components consisting of from about 85% to about 90% acrylonitrile, from about 1% to about 10% of a copolymerizable monomer selected from the group consisting of ethylenically unsaturated sulfonic acids and their water-soluble salts, and from zero to about 14% of a different copolymerizable ethylenically unsaturated monomer.

3. In a process for level dyeing with a basic dyestuff fibers of an acrylonitrile polymer having from about 50 to 600 milliequivalents per kilogram of polymer of anionic groups attached to the polymer chain and comprised of' copolymerized monomeric components consisting of from about 85% to 95% acrylonitrile, from about 1% to about 10% of a copolymerizable monomer selected from the group consisting of ethylenically unsaturated sulfonic acids and their water-soluble salts, and from zero to about 14% of a different copolymerizable ethylenically unsaturated monomer, the steps comprising chemically combining with said polymer before forming fibers therefrom about 0.01% to about 0.3% by weight of magnesium by polymerizing said monomeric components in the presence of magnesium bisulfite, extruding said polymer to form said fibers, and thereafter conducting the dyeing of said fibers in a dye bath containing said basic dyestuif.

4. The process of claim 2 wherein said magnesium is present in an amount from about 0.16% to about 0.24% by weight of said polymer and said magnesium is combined with said polymer by reacting with said components to form said polymer a member selected from the group consisting of magnesium bisulfite and magnesium sulfate. 7 5. In a process for level dyeing composite fibers preppared from different acrylonitrile polymers wherein the first of said polymers has from about 50 to about 600 milliequivalents per kilogram of polymer of anionic groups attached to the polymer chain and the other of said polymers has up to about 5 0 milliequivalents per kilogram of polymer of anionic groups attached to the polymer chain, the steps comprising chemically combining with said first polymer from about 0.01% to. about 0.3%

8 by weight of magnesium, extruding said polymers through a commonv orifice to form said composite fibers and thereafter conducting the dyeing of the fibers so formed in a bath containing a basic dyestufi.

6. The process of claim 5 wherein said first polymer is comprised of copolymerized monomeric components consisting of from about to about 99% acrylonitrile, from about 1% to about 10% of a copolymerizable monomer selected from the group consisting of ethylenically unsaturated sulfonic acids and their water-soluble salts, and from zero to about 14% of a different copolymerizable ethylenically unsaturated monomer.

7. In a process for level dyeing composite fibers prepared from different acrylonitrile polymers wherein the first of said polymers has about 50 to about 600 milliequivalents per kilogram of polymer of anionic groups attached to the polymer chain and is comprised of copolymerized monomeric components consisting of from about 85% to about 99% acrylonitrile, from about 1% to about 10% of a copolymerizable monomer selected from the group consisting of ethylenically unsaturated sulfonic acids and their water-soluble salts, and from zero to about 14% of a different copolymerizable ethylenically unsaturated monomer, and the other of said polymers has up to about 50 milliequivalents per kilogram of polymer of anionic groups attached to the polymer chain, the steps comprising chemically combining with said first polymer before forming fibers therefrom from about 0.01% to about 0.3% of magnesium by polymerizing said monomeric components in the presence of mag nesium bisulfite, extruding said polymers through a common orifice to form said composite fibers and thereafter conducting the dyeing of the fibers so formed in a bath containing a basic dyestuff.

8. The process of claim 7 wherein said magnesium is present in an amount from about 0.16% to about 0.24% by weight of said first polymer.

9. A textile fiber having level dyeing characteristics when dyed with a basic dyestufi, said fiber being prepared from an acrylonitrile polymer having from about 50 to about 600 milliequivalents per kilogram of polymer of anionic groups selected from the class consisting of sulfate and sulfonate groups attached to the polymer chain, and having from about 0.01% to about 0.3% by weight of magnesium chemically bonded to said anionic groups.

10. The fiber of claim 9 wherein said polymer is comprised of copolymerized monomeric components consisting of from about 85% to about 99% acrylonitrile, from about 1% to about 10% of a copolymerizable monomer selected from the group consisting of ethylenically unsaturated sulfonic acids and their water-soluble salts, and from zero to about 14% of a difierent copolymerizable ethylenically unsaturated monomer.

11. The fiber of claim 10 wherein said magnesium is present in an amount from about 0.16% to about 0.24% by weight of said polymer.

12. A composite textile fiber comprised of dissimilar polymer compositions extending in adhering contact with each other along the length of the fiber having level dyeing characteristics, one of said compositions being an acrylonitrile polymer having from about 50 to about 600 milliequivalents per kilogram of polymer of anionic groups selected from the class consisting of sulfate and sulfonate groups attached to the polymer chain and having from about 0.01% to about 0.3% by weight of magnesium chemically bonded to said anionic groups, and the other of said compositions being an acrylonitrile polymer having less than 50 milliequivalents per kilogram of said anionic groups on the polymer chain.

13. The fiber of claim 12 wherein said magnesium is present in the one polymer composition in an amount from about 0.16% to about 0.24% by weight of said polymer.

(References on following page) 9 10 References Cited in the file of this patent 2,913,438 Davis et a1 Nov. 17, 1959 UNITED STATES PATENTS 3,043,811 Traylor et a1 July 10, 1962 1,921,947 Schneevoigt et a1 Aug. 8, 1933 OTHER REFERENCES 2,215,196 Schlack Sept. 17, 1940 5 Dorset: The Textile Manufacturer, October 1957, pp.

2,822,385 Estes Feb. 4, 1958 51 522 g 55 AB Li 2,837,501 Millhiser June 3, 1958 

1. IN A PROCESS FOR LEVEL DYEING WITH A BASIC DYESTUFF FIBERS OF AN ACRYLONITRILE POLYMER HAVING FROM ABOUT 50 TO ABOUT 600 MILLIEQUIVALENTS PER KILOGRAM OF POLYMER OF ANIONIC GROUPS ATTACHED TO THE POLYMER CHAIN, THE STEPS COMPRISING CHEMICALLY COMBINING WITH SAID POLYMER BEFORE FORMING FIBERS THEREFROM FROM ABOUT 0.01% TO ABOUT 0.3% BY WEIGHT OF MAGNESIUM, EXTRUDING SAID POLYMER TO FORM SAID FIBERS, AND THEREAFTER CONDUCTING THE DYEING OF SAID FIBERS IN A DYE BATH CONTAINING SAID BASIC DYESTUFF. 